The amino nitrogen of the arylamine carcinogen 2-acetylaminofluorene (AAF) must be oxidized into the N-hydroxy compound (N-OH-AAF) in order to be a more potent form of the carcinogen. 2-Nitrosofluorene (NOF) can be formed from N-OH-AAF by 2 routes: 1) deacylation of N-OH-AAF and subsequent oxidation of N-hydroxy-2-aminofluorene and 2) by the free radical activation route which involves the nitroxyl free radical of N-OH-AAF. We have discovered a new reaction which involves 2-nitrosofluorene (NOF) addition to carbon-carbon double bonds of lipid molecules to form a free radical which we postulate to be the nitroxyl free radical form of NOF covalently bound to the unsaturated lipid molecule. The proposed chemical nature of the product of this reaction has a structure very similar to a very potent form of the carcinogen. NOF will not add to saturated lipids and in peroxidizing lipids, the rate of the reaction as well as the products of the reaction are influenced by antioxidants. Therefore, we believe our observations are pertinent to the general observations that polyunsaturated fats enhance and antioxidants depress carcinogenesis. We propose to elucidate the molecular events in the reaction of NOF with oleic acid (one double bond) and determine if the product is mutagenic in the Ames mutagenic tester strains of Salmonella; and if it is found to be mutagenic then determine its carcinogenicity. We also propose to determine the orientation of the product in membranes and whether this product is transferred from the membrane to DNA. We plan to determine if the product reacts with DNA and if this reaction is influenced by antioxidants. We also plan to determine if NOF, when it interacts with nuclear membranes, yields the free radical observed in model membranes and if the rate of formation of the free radical or its stability are influenced by antioxidants.